Mammograms at 40
ACOG Endorses Annual Mammograms for Women Starting at Age 40
According to a newly published clinical guideline from the American College of Obstetricians and Gynecologists (ACOG), annual screening mammography should begin at age 40 for women with an average risk of developing breast cancer. Writing in the August 2011 issue of Obstetrics & Gynecology, the authors cite the brief “sojourn time”—the time from when a tumor is detected to when a patient becomes symptomatic—in this age group as the reason to perform annual mammograms. Although women in their 40s have a lower overall incidence of breast cancer compared with older women, the window to detect tumors before they become symptomatic is shorter. Among women in their 40s, a small asymptomatic tumor progresses to symptomatic cancer within 2.0 to 2.4 years, as compared with 4.0 to 4.1 years for women ages 70 to 74.
ACOG previously advised women in their 40s to have screening mammograms every one to two years and to begin annual screening at age 50.
Two years ago the U.S. Preventive Services Task Force (USPSTF) advised women younger than 50 to review the potential benefits and harms of screening mammography with their healthcare providers before deciding on a course of action. Moreover, the task force recommendations stipulated biennial rather than annual mammography.
The new ACOG guideline brings the organization in line with other groups that have established screening recommendations. The American Cancer Society and the National Comprehensive Cancer Network both recommend annual mammograms beginning at age 40, and the National Cancer Institute recommends screening every one to two years beginning at age 40.
ACOG also notes that “women should be educated on the predictive value of the test and the potential for false-positive results and false-negative results.” Women should also be informed of the potential for additional imaging or biopsies that may be recommended based on screening results, the guideline stresses.
The College continues to recommend annual clinical breast exams (CBE) for women ages 40 and older, and every one to three years for women ages 20 to 39. Additionally, The College encourages “breast self-awareness” for women ages 20 and older. Enhanced breast cancer screening, such as more frequent CBEs, annual MRI (magnetic resonance imaging), or mammograms before age 40, may be recommended for women at high risk of breast cancer. Breast MRI is not recommended for women at average risk of developing breast cancer.
According to The College, there is no consensus on the upper age limit for mammograms, although the benefits of screening declines with increasing age compared with the harms of overtreatment. Women 75 and older should discuss with their healthcare provider whether to continue getting mammograms.
Breast cancer is the second leading cause of all cancer-related deaths among American women. The incidence of breast cancer in the United States declined 2% each year between 1999 and 2006, and deaths from breast cancer have also declined steadily over the past two decades. Evidence suggests the drop in breast cancer rates is most likely due to fewer women getting mammograms and therefore not being diagnosed, as well as a significant drop in women using hormone therapy for menopausal symptoms.
Published on July 26, 2011
- Practice bulletin no. 122: breast cancer screening. Obstet Gynecol. 2011;118(2 Pt 1):372-382.